GB2224737A

GB2224737A - Water base ink compositions for neon boards

Info

Publication number: GB2224737A
Application number: GB8925777A
Authority: GB
Inventors: Kiyotaka Imagawa; Yasuji Okuda
Original assignee: Sakura Color Products Corp
Current assignee: Sakura Color Products Corp
Priority date: 1988-11-15
Filing date: 1989-11-15
Publication date: 1990-05-16
Anticipated expiration: 2009-11-15
Also published as: DE3938001A1; GB2224737B; JPH02133478A; JP2706960B2; GB8925777D0

Description

2224737 1 WATER BASE INK COMPOSITIONS FOR NEON BOARDS This invention

relates to a water base ink composition which forms erasable and light-scattering writings or markings on impervious surfaces of transparent panels or. neon boards' such as of resins or glass. The inventioa further relates to a neon board having writings thereon formed with such an ink composition, a method of preparing a neon board using such an ink composition, and a marking pen suitably used for writing to prepare neon boards.

Display means are already known which are composed of transparent panels such as of resins or glass having on either surface thereof markings or writings and light sources placed at one of the side faces. When the side face receives light incident perpendicularly into the panel, the light travels towards the other side face between the surfaces of the panel and scatters outwards at the writings to brighten them as if the writings emitted light. These 2 display means may be associated with neon signs and will be called herein "neon boards". The transparent panels are composed preferably of highly refractive materials, and most preferably of polymethyl methacrylate.

Heretofore, there have been used ordinary nonerasable water base ink compositions to form writings on the panels. Solvent base erasable ink compositions for use in marking pens have also been used which contain chromatic pigments and white pigments dispersed in organic solvents such as ketones or alcohols.

However, these ink compositions are not specifically designed to be suitably applied to neon boards. Thus, the prior ink compositions are insufficient in light scattering properties and are rather poorly brightened. As a further defect, the prior solvent base erasable ink compositions for use in marking pens usually employ titanium dioxide as white pigments. Titanium dioxide is superior in biding power, but it has a large specific gravity and a large particl e size, and hence it is poorly dispersible in ink compositions. Therefore, titanium dioxide can not be used in marking pens which contain an absorbent ink reservoir and a pen tip connected thereto, since titanium dioxide deposits in the ink reservoirs.

Such marking pens are well known in the art. For instance, the absorbent ink reservoir is a microporous 1 3 absorbent body composed of fibrous or felt-like material or any other suitable absorbent material and likewise a microporous pen tip connected thereto to which inks are supplied by the ink reservoir through capillarity of the microporous networks. Pen tips are also known which are composed of molded resins; they are called plastic pens.

White pigments of smaller particle size may be superior in dispersibility in ink compositions, but the compositions are poorly light-scattering so that they are not suitably used for preparing neon boards.

Asa further defect, ketones used in 1Drior solvent base erasable ink compositions for marking pens are very toxic organic solvents. Methanol is also a toxic alcohol, and smells bad. Ethanol is less toxic, but is expensive.

On the other hand, a water base erasble ink composition is also known which contains a resin emulsion such as a polyvinyl acetate emulsion as a separating agent together with a dyestuff or a pigment as a coloring agent, and a surfactant. However, when writings are formed with such an ink composition on an impervious surface and dried, the resin emulsion forms a continuous adhesive film on the impervious surface, as is the case with a known so-called strippable paint. Consequently the writing is not so easily separated or erased from the surface by light wiping with, 1 25 4 for example, soft cloth or tissue paper. Moreover, when the writing is rather strongly wiped, it is separated as a continuous film from the surface. Particularly, even when the writing is wiped only at a part thereof, it often happens that the entire writing is separated from the writing surface. Moreover, it is fatal that the writings formed therewith on the panels are poorly brightened.

The invention can provide an ink composition suitable for use for providing writings on neon boards which is not only intensely. and vividly brightened but also readily erased at wiped portions from the neon boards, and further, which is suitable for use in marking pens which employ an absorbent ink reservoir and a pen tip connected thereto.

Also the invention can provide a method of preparing a neon board and the thus prepared neon board, -Also the invention can provide a marking pen suitable for use for writing on a panel to prepare a neon board.

There is provided in accordance with the invention a water base ink composition for writing on neon boards which comprises:

(a) water in amounts of not less than 30 % by weight; (b) hollow resin particles dispersed in the water in 1 6 amounts of 0.5-50 % by weight; (c) a resin which is water soluble and film-forming at room-temperature in amounts of 0.5-30 % by weight; and (d) an aqueous emulsion of at least one nonvolatile or only slightly volatile compound which is liquid at room temperature and is selected from the group consisting of aliphatic carboxylic acid esters, higher hydrocarbons and higher alcohols in dry amounts of 0.5-25 % by weight.

The ink composition of the invention contains water as solvent in an amount of not less than 30 % by weight, preferably not less than 50 % by weight, based on the ink composition. When the amount of water is less than 30 % by weight, the resultant ink compositions are so viscous that they write badly.

The ink composition contains therein hollow resin particles in the form of an aqueous emulsion to increase light-scattering properties of writings formed on neon boards. The hollow resin particles are already known as plastic pigments and are used as white pigments in water base ink compositions, as described in Japanese Patent Laid-open No. 63-145382 and No. 63-145383.

The hollow resin particles are usually obtained by emulsion (co)polymerization of one or more of styrene, acrylic acid, acrylic ester, methyl methacrylate or vinyl chloride. Thus, the hollow resin particles are available as aqueous emulsions-of (co)polymers such as polystyrenes, acrylic/styrene copolymers, polymethyl methacrylates or polyvinyl chlorides. The hollow resin particles usually have a specific gravity of not more than one, a particle size of about 0.1-1.0 /im and a refractive index of 1.41.6. Aqueous emulsions of such hollow resin particles are available, for example, as Voncoat or Grandol, both being acrylic/styrene copolymers, by Dainippon Ink Kagaku Kogyo R.K., Opaque Polymer (acrylic/styrene copolymers) by Rohm & Haas Japan K.K., or Latex SBL 8801 (polystyrene) by Asahi Rasei Kogyo K.K.

The hollow resin particles are contained in solid amounts of not less than 0.5 % by weight, preferably of not less than 10 % by weight, based on the ink composition. When the amount of the hollow resin particles is less than 0.5 % by weight based on the ink composition, the resulting ink compositions are insufficient in light-scattering properties, so that writings on neon boards are not intensely brightened. On the other hand, it is desired that the hollow resin particles are contained in amounts of not more than 50 % by weight, preferably of not more than 40 % by weight, based on the ink composition, from the standpoint of stability and adhesion of ink compositions 7 onto neon boards.

Further, it is desired that the hollow resin particles used in the invention have a particle size of 0.2-0.6 pin from the standpoint of 1 ight- scattering power and stability of dispersion in ink compositions.

The hollow resin particles act both as lightscattering agents and white colorants. Thus, the use-of the hollow resin particles only as colorants provides white ink compositions. Achromatic(other than white), or chromatic ink compositions are obtained by employing, as colorants, dyes which are preferably water soluble, or pigments which have a particle size preferably of 0.01-1 tim. Water insoluble dyes may also be used as a coloring agent, if necessary. The water insoluble dyes used preferably have a particle size of 0.01-0.7 U;P, and the dyes are dispersed in water using a suitable dispersant.

As coloring agents, any pigment may be used, and the pigments usable include, for example, carbon black, phthalocyanines such as copper phthalocyanine blue, azo pigments, quinacridones, anthraquinones, dioxazines, indigos, thioindigos, perynones, perylenes, indolenones and azo-azomethines.

A variety of aqueous pigment dispersions are commerciaIly available, and they may be preferably used in the invention. The dispersion usually contains a dispersant 8 and/or a surfactant, so that the ink composition of the invention may contain such a dispersant and/or a surfactant when the dispersion is used in the ink composition. The dispersant is usually of-organic polymer and is contained in the dispersion usually in amounts of 1-300 parts by weight, preferably in amounts of 5-100 parts by weight, per one part by weight of pigment.

In place of pigments or dyes, hollow resin particles colored with dyes canproduce chromatic ink compositions of the invention.

The content of coloring agent in the ink composition is usually not more than 20 % by weight, preferably not more than 10 % by weight. When the content of coloring agents is too large, the resultant ink compositions have an excessively high viscosity so that they write badly, but also they are reduced in erasability, and further, writings formed therewi th are not intensely brightened.

The ink composition of the invention contains a resin which is water. soluble and film-forming at room tempera- ture to improve leveling properties of writings on neon boards and dipersibility of any coloring agents used in the ink compositions.

As such water soluble and film-forming resins, there are used either resins which are water soluble by nature, aqueous emulsions or hydrosols of water insoluble resins, 9 or water-solubilized resins. The water-solubilized resins are in this specification defined as resins which are by nature water insoluble, but are made water-soluble by salt formation with inorganic or organic bases, such as alkali metal salts, e.g., sodium or potassium salts, ammonium salts or amine salts.

There may be mentioned as resins which are water soluble by nature, for example, synthetic resins such as polyvinyl pyrrolidone or polyvinyl resins such as shellac or gum arabic.

The emulsions or hydrosols of by nature water insoluble resins usable include, for example, those of polyvinyl acetates, vinyl acetate copolymers, styrenemaleic anhydride resins, alkyd resins or urethane resins.

The water-solublized resins usable include, for example, water-solublized polyvinyl acetates, vinyl acetate copolymers, alkyd resins and urethane resins.

The vinyl acetate copolymers mentioned above include copolymers of vinyl acetate with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, crotonic acid or citraconic acid, vinyl esters other than vinyl acetate, such as vinyl propionate, vinyl hydrocarbons such as ethylene, propylene, butene, styrene, ot-methylstyrene, acrylic or methacrylic acid esters such alcohol, or natural as methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate or dimethyl maleate. The vinyl acetate copolymer may be a graft one with the monomers as above described onto Polyvinyl acetates.

Preferred vinyl acetate copolymers may be exemplified by vinyl acetateacrylic acid copolymer, vinyl acetatemethacrylic acid copolymer, vinyl acetate-styrene-acrylic acid copolymer, vinyl acetate-styrenemaleicanhydride copolymer, vinyl acetate-acrylic acid-methyl acrylate copolymer, vinyl acetate-methacryli.c acid-methyl acrylate copolymer, vinyl acetate-acrylic acid-ethyl acrylate copolymer, vinyl acetatemethacr.ylic acid-methyl methacrylate copolymer and vinyl acetate-maleic anhydride copolymer. The vinyl acetate coplymers are usually water insoluble, however, the inorganic or organic salts thereof are water soluble. These water-solubilized copolymers are commercially available.

Similarly, the water-solubilized-a-lkyd resins may be prepared by condensation of excessive unsaturated carboxylic acids with polyhydric alcohols, and salt formation with alkali metal bases, ammonium bases or organic amines. The water-solubilized urethane resins may be prepared by saltformation of pendant carboxylic groups in the polymer chain with alkali metal bases, ammonium bases or organic amines. These water-solubilized alkyo. resins and urethane 11 resins are also commercially available.

The water soluble or water-solubilized resin is contained in the fnk composition in amounts of 0.5-30 % by weight, preferably in amounts of 120 % by weight, based on the ink composition. When the amount of the resin is too large, the resultant ink composition has an excessively high viscosity so that it writes badlybut also writinps formed therewith are not -readily erased.

The ink composition of the invention contains water soluble resins, watersolubilized resins or emulsions or hydrosols of water insoluble resins as above described. As aresult,when writings are formed on neon boards with the ink composition, the resin forms a film which contains the hollow resin particles and colorants therein. Particularly, the resin acts as a carrier of the hollow resin particles and colorants. Therefore, the use of emulsions of by nature water insoluble resins or resins which are by nature water insoluble but are made water soluble by salt formation is in particular.preferred in the invention, since ink compo- sitions containing such resins provide writings which are not only water resistant but also erasable irrespective of ambient conditions of temperature and humidity.

The ink composition of the invention contains a separating agent which is an aqueous emulsion of at least one nonvolatile or only slightly volatile compound which 12 is liquid at room temperature and is selected from the group consiting of aliphatic carboxylic acid esters, higher hydrocarbons and higher alcohols.

The aliphatic carboxylic. acid ester includes monobasic carboxylic acid esters, dibasic carboxylic acid diesters, mono- or diesters of dihydric alcohols, and mono-, di- or triesters of trihydric alcohols. More specifically, there may be used monobasic carboxylic acid esters, preferably higher fatty acid esters such as ethyl oleate, butyl laurate, hexyl laurate, isostearyl laurate, oleyl 2-ethylhexanoate, ethyl isostearate, butyl stearate, is opropy I myris ta te, buty I pa I mi tate, isoocty I pa I mi tate, isooctadecyl palmitate, isooctyl stearate and isooctadecyl stearate; dibasic acid diesters such as dodecanedioic acid dioctyl ester, dipropyl adipate, dioctyl sebacate or dioctyl azelate; dihydric alcohol esters such as propylene glycol monostearate or propyleneglycol didecanoate; and trihydric alcohol esters such as natural or synthetic fatty acid tri.glycerides, for example, caproic acid triglyceride, carprylic acid triglyceride, lauric acid triglyceride, 2hexyldecanoic acid triglyceride or the like. The triglyceride may be a mixed triglyceride in which the fatty acid components are different from each other. Further, the triglyceride may be used singly or as a mixture. Fatty acid trimethylolpropane triesters such as 13 triisostearate may also be used.

The higher hydrocarbon used as a separating agent is not specifically limited, but may be exemplified by liquid paraffin and squalane. Oxydized polyethylene wax may also be used. The higher alcohol used is also not specifically limited, but may be exemplified by hexyl alcohol, octyl alcohol and lauryl alcohol.

Aqueous emu I s i ons of the a I i pha ti c carboxyl ic a c i d esters, higher hydrocarbons or higher alcohols may be prepared by conventional emulsifying methods, and are commercially available. The emulsion may be used singly or as a mixture of two or more.

The emulsion is contained in the ink composition of the invention so that the aliphatic carboxyl ic acid ester, higher hydrocarbon, higher alcohol or a mixture of two or more of these is contained in dry amounts of 0.525 % by weight, preferably in amounts of 5-15 % by weight, based on the ink composition. When the amount of the liquid compound, i. e., the ester, hydrocarbon or alcohol, is less than 0. 5 % by we i gh t based on the i nk compos i t i on, the resultant ink composition is not readily erasable or separable from a panel, whereas when the amount of the liquid compound is more than 25 % by weight, the resultant ink composition stains a panel when being wiped. Further, writings formed therewith are not readily erased.

14 The ink composition of the invention may contain a water soluble polyhydric alcohol to assist the separation of writings from writing surfaces. The polyhydric alcohol usable includes, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol having a molecular weight of about 200-600, polypropylene glycol having a molecular weight of about 1000-3000, glycerine and trimethylolpropane. The polyhydric alcohol may be contained in amounts of not more than 20 % by weight, preferably in amounts of not more than 10 % by weight, based on the ink composition. When the amount of the polyhydric alcohol is too large, the resultant ink composi ti on has an excessive I y I arge viscosity and writes badly.

A variety of surfactants, either anionic, nonionic, cationic or ampholytic, may also be incorporated in the ink composition as a writing separation assistant. Among the surfactants are preferred polyoxyethylene carboxylic acid, sulfonic acid, sulfate or phosphate nonionic or anionic surfactants, ampholytic betaine surfactants or fluorinated surfactants. The amount of surfactants may be not more than 10 % by weight, preferably in the range of 0.2-5 % by weight based on the ink composition. The use of excessive amount deteriorates erasability of the ink composition.

Although the invention is not limited by any theory, we suggest that when writings are formed on an impervious writing surface with a marking pen, and when the water has been evaporated or the writing has been dried, the resin forms a film which contains the hollow resin particles and the pigment, while the emulsion of the separating agent is broken to form a continuous oily layer between the writing surface and the resin film, and therefore the writing is separable or erasable from the surface by being wiped.

The surfactant assists the separation of the oily layer from the resin layer when writings are formed. Moreover, the surfactant provides a levelling effect with writings formed and also prevents the emulsion from being unevenly distributed on a writing surface when writings are formed, so that the dried writing is evenly erasable. From these standpoints, fluorinated surfactants are most preferred.

Lower aliphatic alcohols may be contained in the ink composition so that writings are readily dried when formed.

However, the alcohol must not break the emulsion in the ink composition, and therefore the amount may be not more than 15 % by weight, preferably in the range of 1-10 % by weight, based on the ink composition. The preferred alcohol may be ethanol, propanol or butanol.

The ink composition may further contain any conven- 16 tional additives used in water base ink compositions, such as pff controllers, anticorrosion agents or dispersion assistants in effective amounts.

As above set forth-, the water base ink composition of the invention contains hollow resin particles which are of a much smaller specific gravity and particle size than titanium dioxide, and are still superior in light-scattering properties.

Thus, in accordance with the invention, there is provided a method of preparing a n.eon board which comprises forming writings on at least one of the flat surfaces of a transparent panel with the ink composition of the invention as described hereinbefore. The writings thus formed on the panel are clearly visible in the dark when light is applied into the panel.

There is further provided a neon board in accordance with the invention which comprises a transparent panel having flat surfaces, a light source placed at one of the side faces thereof and writings formed with the ink composition of the invention on at least one of the surfaces of the panel.

Further, since the hollow resin particles are excellent in dispersibility in the ink composition,j:j contrast to titanium dioxide, there takes place no deposition or coagulation of the particles even after a long 17 period of standing of the ink composition. Thus, in accordance with the invention, there is provided a marking pen which employs'an absorbent ink reservoir impregnated with such an ink composition as described hereinbefore and a pen tip connected thereto, for use in writing on a transparent panel and thus suitably used for preparing a neon board.

As a further feature, the ink composition of the invention has low toxicity, and is attended by very little bad and irritant smell since it has a water base. Further, the ink composition of the invention contains a water soluble and film forming resin together with a separating agent. The separating agent forms a continuous oily layer on the surface to separate the layer of the resin which contains the hollow resin particles therein from the writing surface, so that the writing is as readily separated from the writing surface as the conventional solvent base erasable ink compositions.

In particular, the separating layer is not a solid film, but an oily one, so that when the writing is wiped only partly, the wiped portions only are erased. Further, since the separating layer is composed of nonvolatile or only slightly volatile liquid compound, writings are readily erasable after long standing.

When the ink composition contains a by nature water 18 insoluble resin in a water-solubilized form, or more preferably as a hydrosol or an emulsion, the resin forms a layer which is highly water resistant as well as readily and stably erasable irrespective of ambient humidity conditions.

The invention will now be described with reference to examples which are not to be construed as limiting to the invention. In the examples, percentages are % by weght.

EXAMPLES

The following ink compositions were prepared which had the compositions below. The percentages designate effective (dry or solid) amounts of ingredients and the balance is water and effective amounts of anticorrosion agents.

Ink Composition 1 Coloring agen-t: Carbon black Dispersant: Nikkol PLP-W' Hollow resin particles: Ropawue OP-84J" Resins: Nowinyl Powder W' Separating agent: Emulsion of butyl stearate Surfactant: Nopco Wet 50 I 6 % 2 % 7 % 10 % 0.5% Ink Composition 2 Coloring agent: Phthalocyanine Blue Dispersant: Joncryl J-682" Hollow resin particles: Grandol PP_11006) Resins: Polysol HR-8E') Separating agent: Emulsion of butyl palmitate Separating assistant: Polypropylene glycol (average molecular weight of 600) Surfactant: Noigen ET-135') Unidyne DS-401" Ink Composition 3 Coloring agent: Monoazo, Yellow Dispersant: Hiros AW-36 Hollow resin particles: Grandol PP-1.000'') Resins: Polyvinyl alcohol 204 Separating agent: Emulsion of squalane Emulsion of dioetyl azelate Surfactant: Neocol SW Ink Composition 4 Coloring agent: None Dispersant: None Hollow resin particles: Latex SBL 8801' Resins: Nikasol CL-204 6 % 2 % 25 % 5.5% 10 % 3 % 2 % 1.5% 1.5% 25 % 6.5% 6 % 5 % 0.5% % 6 % Separating agent: Isopropyl myristate Toray Silicone SF 8427 16) Surfactant: Fluorad F-430 17) Ink Composition 5 Coloring agent: NLA-655 Scarlet"' Dispersant: None Hollow resin particles: Grandol PP-1001' 9) Resins: UMR Resin 10HH"' Separating agent: Emulsion of octyl stearate Separating assistant: Polypropylene glycol (average molecular weight of 1000) Surfactant: Anhitol 24B Ink Composition 6 Coloring agent: Blue No. 1 Dispersant: None Hollow resin particles: Grandol PP-1000 Resins: Mowinyl Mfl 20 Separating agent: Liquid paraffin 150-S emulsion Surfactant: Neokol SW Comparative Ink Composition 7 Coloring agent: Phthalocyanine Blue Dispersant: Nikkol DLP-10 i 8 % 2 % 1 % % 1.5% 30 % 6 % 5 % 3 % 3 % 4 % 1.5% 35 % 5 % 8 % 1 % % 2 % A 21 Hollow resin particles: Grandol PP-1100 Resins: Mowinyl Powder SA Separating agent: None Surfactant: Nopco Wet 50- Comparative Ink Composition 8 Coloring agent: Phtbalocyanine Blue Dispersant: Nikkol DLP-10 Hollow resin particles: Mowinyl 972 23) Resins: Mowinyl Powder SA Separating agent: Emulsion of butyl stearate Surfactant: Nopeo Wet 50 Comparative Ink Composition 9 Coloring agent: Phthalocyanine Blue Dispersant: Nikkol DLP-10 Hollow resin particles: Mowinyl 972 Resins: Mowinyl Powder SA Separating age,nt: None Surfactant: Nopeo Wet 50 % 7 % 0.5% 2 20 7 % 0.5% % 2 % % 7 % 0.5% N o, t e s: 1) Nonionic surfactant, Nihon Surfactant Kogyo K.K. 2) Hollow resin particles of acrylic/styrene copolymers, Rohm & Haas Japan.

22 8) 9) 10) 11) 15) 16) 17) 18) 19) 3) Vinyl acetate/acrylic copolymers, Hoechst Gosei R.K. 4) Aninoic surfactant, San Nopco Ltd. 5) Acrylic/styrene copolymers, Johnson Polymer X.X. 6) Hollow resin particles of acrylic/styrene copolymers, Dainippon Ink Kagaku Kogyo K.K. Emulsion of vinyl acetate/acrylic copolymers, Showa Kobunshi K.K. Nonionic surfactant, Daiichi Kogyo Seiyaku K.X. Fluorinated surfactant, Daikin Kogyo K.K. Acrylic resins, Seiko Kagaku KA. Hollow resin particles of acrylic/styrene copolymers, Dainippon Ink Ragaku Kogyo K.K. 12) Polyvinyl alcohol, Kuraray K.K. 13) Nonionic surfactant, Daiichi Kogyo Seiyaku K.K. 14) Hollow resin particles of polystyrene, Asahi Kasei Kogyo X.R. Vinyl acetate/acrylic copolymers, Nihon Carbide K.K. Alcohol- modified silicone, Toray K.K. Fluorinated surfactant, Sumitomo 3M K.K. Pigment dispersion Hollow resin particles of acrylic/styrene copolymers, Dainippon Ink Xagaku Kogyo X.K. 20) Saponified polyvinyl acetate, Unitika Kasei K.K. 21) Ampholytic surfactant, Kao K.K. 22) Vinyl acetate/maleate copolymers, Hoechst Gosei K.X.

1 1 23 23) Emulsion of soild resin particles, Hoechst Gosei K.K Writings of about 2 x 2 cm were provided on writing boards of transparent polymethyl methacrylate using the above ink compositions. The boards were placed in the dark, and light was applied from one of the side faces perpendicu larly into the panels, and the panels were tested as to whether the writings were clearly visible in the dark from a place five meters apart therefrom (visibility).

Further writings were provided on writing boards of transparent polymethyl methacrylate using the above ink compo sitions, left standing, and then wiped lightly with dry cloth, to evaluate erasability of the writings after five minutes (initial erasability) and after one week (standing erasability), at a temperature of 257C under a relative humidity of 60 %. The erasability was evaluated with the eyes: A, readily erasable; B, fairly erasable; C, only slightly erasable; and D, not erasable. The results are shown in the Table 1.

For comparison, the same erasability tests were carried out with conventional solvent base erasable ink compositions containing ketones and alcohols as solvents, respectively, and titanium dioxide as colorants. The results are shown in Table 1.

11 24 Table 1

Erasability Ink Compositions Visibility Initial Standing Conventional P' A c D 2 A c D A A A 2 A A A 3 A A A 4 A A B A A A 6 A A B 7 A c D 83) D A A 93) D c D Notes: 1) Contains ketones as a solvent. 2) Contains alcohols as a solvent. 3) Comparative examples The water base ink composition of the invention 20 contains no titanium dioxide, but is comparable with th solvent base compositions in the visibility in the dark. Further, the ink composition of the invention retains erasability comparable tothe conventional water base erasable ink compositions.

Claims

Claims

A water base ink composition for writing on neon boards which comprises:

(a) water in amounts of not less than 30 % by weight; (b) hollow resin particles dispersed in the water in amounts of 0.5-50 % by weight; (c) a resin which is water soluble and film-forming at room temperature in amounts of 0.5-30 % by weight; and (d) an aqueous emulsion of at least one nonvolatile or only slightly volatile compound which is liquid at room temperature and is selected from the group consisting of aliphatic carboxylic acid esters, higher hydrocarbons and higher alcohols in dry amounts of 0.5-25 % by weight.
2. The ink composition as claimed in claim 1 wherein the resin is a by nature water soluble resin, or a resin which is by nature water insoluble, but is made water soluble by salt formation with bases, or a resin which is by nature water insoluble, but is in the form of aqueous emulsion or hydrosol.
3. The ink composition as claimed in claim 2 wherein 26 the by nature water soluble resin is polyvinyl alcohol.
4. The ink composition as claimed in claim 1 wherein the by nature water insoluble resin is polyvinyl acetate, vinyl acetate copolymer, styrene-maleic anhydride copolymer, alkyd resin or polyurethane resin.
5. The ink composition as claimed in claim 1 which further contains a water soluble polyhydric alcohol in amounts of not more than 20 % by weight based on the ink composition.
6. The ink composition as claimed in claim 1 which further contains a lower aliphatic alcohol in amounts of not more than 15 % by weight based on the ink composition.
7. The ink composition as claimed in claim 1 wherein the aliphatic carboxylic acid ester is a monobasic carboxylic ac,id ester, a dibasic carboxylic acid diester, a mono- or diester of a dihydric alcohol, or a mono-, dior triester of a trihydric alcohol.
8. The ink composition as claimed in claim 1 wherein the higher hydrocarbon is liquid paraffin or squalane.

27
9. The ink composition as claimed in claim 1 wherein the higher alcohol is hexyl alcohol, octyl alcohol or lauryl alcohol.
10. The ink composition as claimed in claim 1 which further contains pigments or dyes as colorants.
11. The ink composition as claimed in claim 1 which further contains surfactants.
12. A neon board which comprises a transparent panel having flat surfaces, a light source placed at one of the side faces of the panel and writings formed on at least one of the surfaces of the panel, the writings being formed with an ink composition which comprises:

(a) water in amounts of not less than 30 % by weight; (b) hollow resin particles dispersed in the water in amounts of 0.5-50 % by weight; (c) a resin which is water soluble and film-forming at room temperature in amounts of 0.5-30 % by weight; and (d) an aqueous emulsion of at least one nonvolatile or only slightly volatile compound which is liquid at room temperatures and is selected from the group consisting of aliphatic carboxylic acid 28 esters, higher hydrocarbons and higher alcohols in dry amounts of 0.5-25 % by weight.
13. A method of prepafing a neon board which comprises forming writings on at least one of the flat surfaces of a a transparent panel with an ink composition which comprises:

(a) water in amounts of not less than 30 % by weight; (b) hollow resin particles dispersed in the water in amounts of 0.5-50 % by weight; (c) a resin which is water soluble and film-forming at room temperature in amounts of 0.5-30 % by weight; and (d) an aqueous emulsion of at least one nonvolatile or only slightly volatile compound which is liquid at room temperature and is selected from the group consisting of aliphatic carboxylic acid esters, higher hydrocarbons and higher alcohols in dry amounts of 0.5-25 % by weight.
14. A marking pen which contains an absorbent ink reservoir therein impregnated with an ink composition and a pen tip connected thereto. for use in writing on a transparent panel, thereby to prepare a neon board, the ink composition comprising:

(a) water in amounts of not less than 30 % by weight; 29 (b) hollow resin particles dispersed in the water in amounts of 0.5-50 % by weight; (c) a resinwhich is water soluble and film-forming at room temperature in amounts of 0.5-30 % by weight; and (d) an aqueous emulsion of at least one nonvolatile or only slightly volatile compound which is liquid at room temperature and is selected from the group consisting of aliphatic carboxylic acid esters, higher hydrocarbons and higher alcohols in dry amounts of 0.5-25 % by weight.
15. A water base ink composition substantially as hereinbefore described with reference to any one of Examples 1-6.
16. A marker pen substantially as hereinbefore described with reference to any one of Examples 1-6.
17. A neon board substantially as hereinbefore described with reference to any one of Examples 1-6.

Pubhshed 1990atThe Patent Office, State House. 66'71 High Holborn. London WCIR4TP.I\lrther copies maybe obtainedfrom The Patent office, Sales Branch. St Mary Cray. Orpington. Kent BR 3RD. Printed by Multiplex techniques ltd. St Mary Cray. Kent. Con. 1 87